Leaves turning yellow

Need help the plants that I'm talking about are 22 days into flowering and the fan leaves are starting to turn yellow at the tips, And some of them are all yellow and falling off im sure this is not really normal so if somone could help me with what I should do it would be nice

If you are three weeks into flowering that is quite normal. As the plants nears the end of its life, when the final buds are produced, it puts all its energy into making flower, bud, so that it will successfully reproduce and its lineage will continue. So when the plant is getting close to being fully mature, it stops wasting energy on vegatative growth, height and leaves, and starting investing heavily in reproductive growth, buds. Since fan leaves are usually storage of nutrients, they begin to wither as the plants pulls all available nutrients from the fan leaves to fuel bud production.